The goal of this project is to increase reading motivation, engagement, and proficiency in struggling readers. Literacy is essential to academic success, responsible citizenship, and optimal health through the lifespan. Research has shown that the motivation to read in the early grades is a significant predictor of later literacy outcoms; an effect largely mediated by the amount of reading a student actually does. Structured silent reading practice using the web-based Reading Plus(r) program has been shown to increase students' ability to comprehend more complex texts and is associated with significant gains on state and third-party reading assessments. Yet many students lack reading motivation and devote little effort to developing their reading proficiency. To address this issue, instructional strategies were examined that have been shown to improve reading motivation, engagement, and achievement in the classroom. Here it is proposed to adapt and incorporate these proven instructional strategies into a motivationally adaptive version of the Reading Plus program, and to evaluate the effectiveness of this approach. In Phase I of this project a prototype of the motivationally adaptive program will be developed that includes: (a) a 24-item on-line motivation inventory measuring four affirming motivations; (b) a performance-based measure of behavioral and cognitive engagement (time on task, persistence, and effort as shown by performance reliability and advancement); and (c) adaptive program logic that will enable performance on these inventories to control the instructional environment (e.g., difficulty trajectory, pace, contnt selections, scaffolds, explicit instruction on strategies and relevance, feedback, and achievement awards). Measures of reading motivation and engagement will then be used to automatically differentiate and optimize instruction for individual students during a ten-week randomized experiment involving 1,600 students in grades six and seven. Significant treatment effects (standard versus adaptive program) on program engagement, motivation, and/or growth in reading achievement will confirm a positive effect of motivationally adaptive Reading Plus instruction. Given favorable results, the prototype will be expanded in Phase II to include a structured interview component for chronicling independent reading activity, and an educator interface component that documents each student's motivational status, engagement, reading performance, and independent reading behaviors. The adaptive version of Reading Plus silent reading program will be made commercially available in Phase III.